Here is the question from GMAC Official Guide 13th edition, question 94 p. 529:

As a construction material, bamboo is as strong as steel and sturdier than concrete. Moreover, in tropical areas bamboo is a much less expensive construction material than either steel or concrete and is always readily available. In tropical areas, therefore, building with bamboo makes better economic sense than building with steel or concrete, except where land values are high.

Which of the following, if true, most helps to explain the exception noted above?

(A) Buildings constructed of bamboo are less likely to suffer earthquake damage than are steel and concrete buildings.
(B) Bamboo is unsuitable as a building material for multistory buildings.
(C) In order to protect it from being damaged by termites and beetles, bamboo must be soaked, at some expense, in a preservative.
(D) In some tropical areas, bamboo is used to make the scaffolding that is used during large construction projects.
(E) Bamboo growing in an area where land values are increasing is often cleared to make way for construction.

David@VeritasPrep wrote:Here is the question from GMAC Official Guide 13th edition, question 94 p. 529:

As a construction material, bamboo is as strong as steel and sturdier than concrete. Moreover, in tropical areas bamboo is a much less expensive construction material than either steel or concrete and is always readily available. In tropical areas, therefore, building with bamboo makes better economic sense than building with steel or concrete, except where land values are high.

Which of the following, if true, most helps to explain the exception noted above?

(A) Buildings constructed of bamboo are less likely to suffer earthquake damage than are steel and concrete buildings.
(B) Bamboo is unsuitable as a building material for multistory buildings.
(C) In order to protect it from being damaged by termites and beetles, bamboo must be soaked, at some expense, in a preservative.
(D) In some tropical areas, bamboo is used to make the scaffolding that is used during large construction projects.
(E) Bamboo growing in an area where land values are increasing is often cleared to make way for construction.

IMO B.

Reason- if land values are high, there will be a temptation to make multi-storied buildings. Take the example of NYC...you'll see more of high-rises since land comes at a premium. Bamboos on the other hand are unsuitable for multi-storied buildings.

OA is B.

This paradox question is often cited as an example of a CR question that requires outside information. The outside information (as Bharat has noted) is that "where land values are high multistory buildings are likely."

With answer choice B added to this assumption, the paradox is explained. Bamboo is a great building material for everywhere except were land values are high.

Is this too big of an assumption? I do not think it is. As Bharat has indicated this is a reasonable assumption to make.

As a construction material, bamboo is as strong as steel and sturdier than concrete. Moreover, in tropical areas bamboo is a much less expensive construction material than either steel or concrete and is always readily available. In tropical areas, therefore, building with bamboo makes better economic sense than building with steel or concrete, except where land values are high.

Which of the following, if true, most helps to explain the exception noted above?

Buildings constructed of bamboo are less likely to suffer earthquake damage than are steel and concrete buildings.

Bamboo is unsuitable as a building material for multistory buildings.

In order to protect it from being damaged by termites and beetles, bamboo must be soaked, at some expense, in a preservative.

In some tropical areas, bamboo is used to make the scaffoldingthat is used during large construction projects.

Bamboo growing in an area where land values are increasing is often cleared to make way for construction.

FACT 1: In tropical areas, building with bamboo makes better economic sense than building with steel or concrete.

FACT 2: There is one EXCEPTION: WHERE LAND VALUES ARE HIGH, building with bamboo DOES NOT make better economic sense.

Why does building with bamboo NOT make better economic sense WHERE LAND VALUES ARE HIGH (in other words, where land is MORE EXPENSIVE)?
Prediction: Building with BAMBOO is somehow linked to using MORE LAND.

B: Bamboo is unsuitable as a building material for multistory buildings.
The implication is that bamboo buildings will need to be single-story and thus will require MORE LAND -- making it less economical to use bamboo WHERE LAND VALUES ARE HIGH.

The correct answer is B.